Hydraulically and pneumatically controlled mount for automatic guns



HYDRAULICALLY AND PNEUMATICALLY CONTROLLED MOUNT FOR AUTOMATIC GUNS 3 Sheets-Sfieet l 6 FIG. 1.

Filed Dec. 27, 1938 79 84 .90 9a '17. wy/10% 2,316,320 oMA rIc aims April 13, 1943.

A. DE WANDRE HYDRAULICALLY AND PNEUMATICALLY CONTROLLED MOUNT FOR AUT Filed Dec. 27. 193a April 13, 1943. DEM/ANDRE 2,316,320

HYDRAULICALLY AND PNEUMATICALLY CONTROLLED MOUNT FOR AUTOMATIC GUNS Filed Dec. 2'7. 193s 3 Sheets-Sheet 3 Patented Apr. 13, 1943 HYDRAULICALLY AND PNEUMIATICALLY CONTRGLLED MOUNT FOR AUTOMATIC GUNS Albert Dewandre, Brussels, Belgium; vested in the Alien Property Custodian A plication December 27, 1938, Serial No. 247,961 In Great Britain August 25, 1938 6 Claims.

The invention relates to turrets for automatic guns installed on aeroplanes, motorised vehicles or other rapidly moving units in which the angular displacements of the gun, about the horizontal and vertical axes of its articulated support, control the running of auxiliary motors for rotating the turret and raising the arch articulated to the latter.

The invention relates more particularly to means actuated by the displacements of the gun about the said axes for operating the distributors which control the admission of fluid to the auxiliary motors.

According to the invention, the fluid distributors controlling the admission of fluid under pressure to the auxiliary motors are controlled by cams actuated by the displacements of the gun about the vertical axis or the horizontal axis of its support, the shape of the cams and the arrangement of the mechanism being such that the gun can undergo, in vertical and horizontal planes simultaneously, considerable angular displacements, beyond the angular displacement necessary for the control of the distributors in order to be directed rapidly towards a given objective, the movable elements of the turret then moving under the action of the servo-motors, to become stationary in the position corresponding to the orientation of the gun.

A preferred embodiment of the invention will now be described, with reference to the accompanying drawings, in which:

Fig. l is a perspective View of the articulated support of the gun comprising mechanisms for controlling the fiuid. distributors.

2 is a diagrammatic View showing the control mechanism applied to the hydraulic-pneuni ic motors, controlling the rotation of a turret and the elevation of the gun on the latter.

Fig. 3 is a side view of a turret provided with the control mechanism showing the possible angular displacements of the gun and its arch in a vertical plane. I

Fig. 4 is an elevation of a turret provided with the control mechanism, showing the angular displacements which the gun can undergo on its support independently of the rotation of the turret.

Fig. 5 is a plan view of the turret corresponding the elevation shown in Fig. 4.

wings, the gun 6 is carried by a supa ulated in a vertical plane, about the pivot :i provided at the end of a fork 8 which is integral with a cylindrical element 9 as shown in Fig. l. The latter is rotatable about a vertical axis on a sleeve H], which is formed at the upper part of a casing H fixed by means of a clamp l2 to an annular frame l3.

The frame I3 is articulated at the hinges l4 (Fig. 3) carried by a movable annular member !5, of the turret, which movable member rolls on a ring [5 rigid with the aeroplane or other unit.

The control mechanism for the actuating fluid effecting the raising of the annular frame l3 comprises cams I! and I8 (Fig. 1) fixed at the lower part of the support to, which during the angular movements of the said support about the pivot l, co-operate respectively with push rods 19 and 2E! symmetrically arranged in the cylindrical element 9 of the support, inside which the push rods extend longitudinally.

The lower end of the push rod l9 which passes into the casing ll, rests on a plate 2| carried by a guiding piston 22 sliding against the action of a spring 23, in a cylindrical chamber 24 formed by the casing II.

The wall of the piston 22 is provided with a notch 25, one edge of which has a slope 26, and in which notch penetrates a push member 2! controlling a compressed air distributor 28 fixed transversely on the casing H.

The distributor 28 has an orifice 29 for the ad mission of compressed air and an orifice 3H for the escape of compressed air, and the orifices are normally isolated from one another by a valve 3! in the form of a piston. The head of the piston is provided with a pad 32 of resilient material and the valve is normally held on its seat 33, formed in the body of the distributor, under the action of a spring 34.

A second valve 35 consisting of a hollow rod slides axially in the distributor body under the action of the push member 27 and against the action of a spring 35. The valve 35 normally establishes communication between the orifice 30 for the escape of compressed air and an orifice 3'? opening to the atmosphere.

When the valve 35 is moved under the action of the push member 21, it closes itself on the head of the piston valve 3!, interrupting the communication between the atmosphere and the orifice so, and then pushes back the valve 3| so as to establish communication between the orifice stand the orifice 29.

The push rod 28 which extends longitudinally into the cylindrical element 9, has at its lower part a slightly off-set cylindrical portion. 23 which is extended in the pivoting axis of the element d and passes through an opening 38 provided in the plate 2|.

The end of the rod 29 rests on the end of a lever 39 secured to a rod 49 of an oil distributor 4| provided transversely to the casing II.

The rod 49 is inserted with a fluid-tight joint in the body of the distributor 4|, and has at its end a needle valve 42 for regulating the passage cross-section or for cutting ofi the communication between the inlet and outlet orifices 43 and 44 for oil under pressure.

The longitudinal displacements of the needle valve 42 are controlled by a quick pitch screw 45 integral with the rod 49, and engaging a corresponding screw thread formed in the body of the distributor 4|.

A piston 43 slides in a cylindrical chamber 46 formed in the casing I I, against the action of a spring 41, and is provided axially with an abutment 49 which acts on the lever 39 and normally maintains it in a position corresponding to the closure of the needle valve 42.

The driving mechanism for raising the frame I3 comprises two hydraulic jacks 59 and 59 mounted on the frame I3. The piston rods of the jacks are articulatedat one end at to the movable annular member I5 and at the other end to thejack piston (not shown in the drawings).

The jacks are fed by an oil pump having a cylinder 54 and a piston 55, the piston rod 56 of which is controlled by a second piston 51 slidable in a compressed air driven cylinder 58, provided preferably in the axial extension of the cylinder 54.

The cylinder 54 of the oil pump is connected by a conduit 43 tothe orifice 43 of the oil distributor 4|, the orifice 44 of which is connected by a c'onduit44 to the jacks 5|! and 59 The motor pump'assembly is fixed in any suitable manner on the frame I3.

, Y The mechanism for controlling actuating fluid effecting the rotation of the movable annular member I5 of the turret, comprises earns 69 and BI as shown in Fig. 1 provided in different transverse planes on the outer cylindrical face of the element 9 of the articulated support of the gun, thesaid cams co-operating respectively with arms 62 and 63 integral with a lever 64, which is articulated at a pivot' 65 carried by the casing II.--

-To' theend of. the'said lever 64 is articulated a-rod 66 of a piston .B'Lwhich slides in a cylinder 68 fixed to the frame I3 by means of a support 69. A fixed stop I9 carried by the cylinder 68 and traversed by the rod 66 serves as a bearing point for a spring 1|,inserted between the said stop and the piston 61. I A flexible pipe 72 connects the cylinder 68 to a cylinder I3,- which is preferably of the same internal diameter as the cylinder 68. A piston I4 provided with arod I5 articulated to a bent lever I6 is slidable in the cylinder 73, the said bent lever I6 oscillating about the pivot II fixed to the body I8 of a group of distributors.

The cylinders 68 and I3 are filled with oil and any displacement of the piston 6! produces a displacement of the piston I4 of the same amplitude.

A return spring I9 fixed at one end to the lever 16 and at the other end to the cylinder I3 balances the spring II and tends to bring said lever I6 into its position of rest with respect to the piston I4.

In the said body I8 are provided two compressed air distributors 89 and 8| similar to the distributor 28 described above, which comprise respectively push members 82 and 83, orifices 84 and 85 for the escape of air under pressure and an orifice 86, common to the said distributors, for the admission of compressed air. The distributors B0 and 8| are controlled by the angular displacements of the lever which is provided with cams B1 and 88, which act respectively on the push members 82 and 83.

The body I8 likewise comprises an oil distributor 89 having a needle valve 89 the said oil distributor being similar to the distributor 4| described above and having inlet and outlet orifices 99 and 9| for the liquid. The stem 92 of the said needle valve 89 is provided at its end with a cam 93 having an S shaped slot 94 in which engages a pin 95 provided at the end of the arm 96 of the bent lever 76.

The slot 94 is formed so as to have at its central part a curved portion having the pivot IT as its centre, in which curved portion the pin '95 can slide under the action of .a certain angular displacement of the lever I6 beyond the normal position of the latter, without imparting to the said cam any movement about its axis of rotation. The end portions of the slot are curved in such a way that when the pin 95 slides therein under the efiect of the angular displacements of the lever 16 towards one or the other end of the slot, a rotary movement always in the same direction is imparted to the cam 93 of the rod 92, so as to cause the needle valve 89 of the distributor 89 to open, while movement of the said lever to its normal position causes the said needle valve to close.

The driving mechanism efiiecting the rotation of the turret preferably consists of compressed air driving cylinders 97 and 98 in which slide respectively pistons 99 and I99, the piston rods WI and I92 of which are each connected to one end of cables I03 and I94. The said cables extend round the movable annular member I5 of the turret in different directions through the medium of pulleys I95 and I96, and are guided round the periphery of the said turret in grooves provided for this purpose in the outer cylindrical face of the annular member I5, the other ends of the said cables being fixed at suitable points to theannular member. The rods I9I and I 92 are also connected together by means of a cable I91 passing over a pulley I99. The said piston rods IIII and I92 form movable oil cylinders in which are provided respectively fixed pistons I99 and H9, the rods III and H2 of which include channels for the passage of oil from the cylinder ID! to the cylinder I92.

The channel of the rod IN is connected by a conduit 99 to the orifice 99 of the oil distributor 89 of the body 18, while the channel of the rod H2 is connected to the orifice 9| of the distributor 89 by a conduit 9P The air cylinder 9'! is connected to the orifice 84 of the air distributor 89 by a conduit 84 while the air cylinder 98 is connected to the orifice of the distributor 8| by a conduit 85 The orifice 89 for the admission of compressed air to the air distributors 99 and BI is connected by a conduit 89 to the compressed air source 59.

The rotation of the turret is effected as follows: In the position of the members shown in Fig. 1, the control mechanism and the driving mechanism are in their positions of rest. If a certain angular movement is now imparted to the gun 6 in the horizontal plane, for example in the direction of the arrow a, so as to point the gun towards a given objective, the displacement of the gun causes the rotation of the element 9, the cam SI of which acts on the arm 63 imparting to the latter and to the lever 64, an angular movement about the pivot 65, the end of the said arm 53 sliding on the periphery of the said cam 6|.

The movement of the lever 64 displaces the piston 61 which forces the liquid contained in the cylinder 68 into the cylinder 13 through the conduit I2, the liquid thus forced in acting on the piston I4 which makes a stroke equal to that made by the piston 61, and displaces the lever I6 angularly against the action of the spring I9.

During the angular movement of the lever I6, the cam 81 forces back the push member 82 of the distributor 89 cutting oi the communication of the conduit 8 with the atmosphere and establishing the communication of the latter conduit with the admission conduit 86 for compressed air, thus allowing the said air to enter the cylinder 91 (Fig. 2).

To permit the actuation of the piston 99 of the cylinder 9! and the movement of the movable annular member I5 of the turret the lever I6 which in its movement progressively opens the distributor 80, must have effected an angular displacement which is sufiicient for the pin 95 of the arm 96, after it has been moved into the central inactive portion oi the slot 94 of the cam 93, to reach the curved end of the said slot which controls the rotation of the rod 92 and the opening of the needle valve 89 of the distributor 89.

The opening of the said needle valve provides communication between the oil cylinders IQI and I92 through the conduits 9|! and 9H, so that the piston 99, subjected to the action of thecompressed air, can then move with a speed which is greater in proportion as the cross-section of the passage allowed by the needle valve of the distributor 89 increases, that is to say in proportion to the amplitude of the angular displacement of the gun.

The movement of the piston 99, under the action of the compressed air, draws the cable I03 which rolls on the pulley I95 and causes the annular member I5 of the turret to rotate, while the oil driven from the cylinder IUI to the cylinder I92, acts on the piston I09 which makes a stroke of the same amplitude as, but in an opposite direction to, that of the piston 99.

When the gun is directed at the given objective by rotation of the turret, it is sufficient to maintain the gun in this direction while the turret, in following its rotary movement, imparts to the cam BI, a movement opposite to that which has been given to cause the rotation of the turret. This reverse movement of the cam causes a corresponding movement of the lever 84, which through the medium of the control mechanism, causes the needle valve 89 to close progressively, finally closing the passage between the conduits 9E! and 9|, and rendering the turret stationary.

If it is desired to rotate the turret again in the same direction after it has stopped, it will be sufiicient to impart to the gun a further angular movement in the direction of the arrow a and the effects described above will be reproduced.

When a rotary movement is imparted to the gun in the direction of the arrow b, so as to point it at a given objective, the cam 69 will act on the arm 62 of the lever 64, which will oscillate about the pivot 65, and drive the piston 61 through the medium of the rod 66 and against the action of the spring II.

The displacement of the piston 6! allows the oil contained in the cylinder I3 to pass into the cylinder 68 into which the oil is forced back by the piston I4 under the action of the spring I9.

When it moves, the piston I4 carries with it the rod I5 and the lever I6, the angular movement of which controls the actuation of the air distributor SI through the medium of the cam 88. The compressed air carried from the source 59 through the conduit 86* then passes into the cylinder 98 through th said distributor 8| and the conduit During the actuation of the air distributor M, the pin of the arm 96 is moved in the slot 94 until it reaches the curved end portion of the said slot, which causes the cam 93 to rotate and the needle valve of the distributor 89 to open, thus establishing a communication between the oil cylinders I (II and I92, after the air distributor 8I has been opened.

The piston I00 thus moves under the action of the compressed air introduced into the cylinder 98 carrying with it in its movement through the medium of the cable I04 the movable annular member I5 of the turret, and the oil contained the cylinder I92 is forced back into the cylinder The speed of rotation of the annular member I5 depends on the cross-section of the passage offered to the oil driven from the cylinder I92 to the cylinder IIlI, the said cross-section being a function of the degree of opening of the needle valve 89 and consequently a function of the amplitude of the movement of the lever 54 controlled by the cam 60.

The rotation of the turret is stopped in the same way as described above for operation in the direction of the arrow a.

In the position of the members shown in Fig. 1 the mechanism controlling the movements of the gun in a vertical plane is in its position of rest, The push rods I9 and 29 are not driven by their respective cams I! and I8, and the driving air cylinder 58 is in communication with the atmosphere through the conduit 39 and the aperture ,37 of the distributor 28, 1e communication between the oil pump cylinder 5% and the jacks 59 and 58 being cut off by the needle valv 32 of the distributor ii.

If the gun is caused to pivot about the axis I in the direction of the arrow 0 so as to point it at a given objective, the cam II acts on the rod I9, which through the medium of the plate 2|, the piston 22 and the incline 2 5 of the notch 25, drives back the push member 2'5 controlling the distributor 23.

The forcing back of the push member 2? has the effect of causing the valve 35 to close itself on the pad 32 of the valve 3i, thus cutting off the communication between the cylinder 58 and the'said needle valve b'eing operated with a certain lag with respect to the distributor 28.

' In effect, the cam I8 is so shaped that it acts on the push rod 20 and consequently on the oil distributor 41 only after the valve SI of the air distributor 28 has been fully opened. During the angular movement of the gun about the pivot 1 'after the said distributor 28has been opened, the cam I8 progressively drives back the push rod 20, which in its longitudinal movement against the action of the spring 41, operates the lever 39, which in its angular movement, drives the shaft 58, thus causing the needle valve 42 to open;

When the said needle valve is opened, communication is provided between the conduits 43 and M so that under the action of the compressed air acting on the piston 57, the oil contained in the cylinder 54 is forced into the jacks 55 and 50 thus causing the frame i3 to rise.

The extent to which the needle valve 42 is opened depends on the shape of the cam 18 which controls the stroke of the push rod 20.

When the gun has acquired the direction of the given objective by raising the frame l3, it is sufficient to maintain it in this direction. The frame in following its rising movement, imparts to the cam IS with respect to the push rod 28, a movement opposite to that which has been given to cause the raising of the frame. Thus the frame I3 is rendered stationary when the push rod 20 engages the cut-away portion of the periphery of the cam i8, whereby the rod 20 rises under the action of the spring 61 and closes the needle valve 42.

' 'If, after stopping the frame l3, it is desired to increase the angle to which the latter is raised,

the gun must again be pivoted about the pivot I in the direction of the arrow when the operation described above will be reproduced.

When the frame I3 is stopped in any raised position, and when it is desired either to bring the frame into its position of rest on the movable annular member of the turret or to point the gun at a given objective situated at a low level, the gun is caused to pivot about the pivot 1 in the direction of the arrow d. During this angular movement of the gun and consequently of the cam H, the push rod [9 slides on the periphery of the said cam 11 and engages the cut-away portion of the latter under the action of the spring 23 which at the same time drives back the piston 22.

The displacement of the piston 22 allows the projection 27 to penetrate the notch 26, thus closing the distributor 28 which cuts off the communication between the source of compressed fluid 59 and the cylinder 58, bringing the latter in communication with the atmosphere through the conduit 39 the valve 35 and the orifice 31.

The cut-away portion of the cam l1 extends to the right end of the latter (as shown in Fig. 1) so that during the angular movements of the gun beyond the horizontal when pointing downwardly, the push rod I9 is not influenced by the cam l1, and the distributor 28 remains in the position in which the cylinder 58 is in communication with the atmosphere.

During this latter movement of the gun, the cut-away portion of the cam I8 situated towards the right, acts on the push rod 2!] and causes the needle valve 42 to open.

Under the weight of the gun and of the mechanism carried by the frame I3, the latter again and 50 is forced through the conduits 43 and 44* into the cylinder 54 of the pump, the piston of which returns to the position shown in Fig. 2 under the effect of the oil pressure.

It should be understood that the rotary movements of the turret and the rising movement of the frame can be effected simultaneously, the movements of one not interfering in any Way with the movements of the other.

The respective cams I1, [8, 6i] and [it are so shaped that when the distribution members occupy a position corresponding to the operation of the turret and/or of the frame, the rotary and/or pivotal movements of the gun can be followed without bearing on the distribution membersand without influencing the position of control given to the said members.

The arrangement of the control of the distribution members has the great advantage that in addition to the maximum angular displacements of frame, the gun can be given a considerable supplementary pivotal angular movement about its horizontal axis.

The large amplitudes of movement of the gun on its support both in a horizontal plane and in a vertical plane, combined with the angular displacements of the turret and of the frame, in the same way, allow the gun to be rapidly directed in a plane parallel to the longitudinal plane of the aeroplane, as shown in Figs. 4 and 5.

What I claim is:

vl. In a gun mount arranged on a moving unit, a stationary ring situated in a horizontal plane and rigid with said unit, a movable annular member rolling upon said stationary ring, auxiliary fluid motors for rotating said movable member in both senses, a casing supported by said movable member, a spindle pivotally mounted in said casing and extending normally in a perpendicular direction with respect to said movable member,

a fork provided at the upper end of said spindle, two branches on said fork; a gun pivotally mounted between said branches; cams arranged in different transverse planes on said spindle and extending around a portion of the periphery of the latter, a two finger forked lever pivoted to said casing, the fingers of said lever cooperating each with one of said cams, fiuid distributors for controlling said auxiliary motors, means subordinated to the angular displacements of said forked lever for actuating said fluid distributors when the gun is being moved laterally off its neutral position, and means subordinated to the sense of such lateral movement of the gun for actuating those distributors which control the motors that impart a corresponding rotary movement to said movable member. I

2. In a gun mount provided on a moving unit, a stationary ring mounted in a horizontal plane on said unit, a movable annular member rolling on said stationary ring, auxiliary fluid motors for rotating said movable member in both senses, a universal joint for supporting the gun onsaid movable member, means actuated by the lateral movements of the gun off the neutral position thereof and about the vertical axis of said universal joint for effecting the angular displacements of an oscillating lever in,either sense in accordance with the sense of the lateral movement communicated to the gun and for maintaining said oscillating lever in its displaced position during the additional lateral displacements communicated to the gun in excess of the displacements necessary for inducing the angular movements of the oscillating lever, two pneumatic fluid distributors secured to a fixed portion of said mount, a tappet for each distributor, two cams for acting each on one of said tappets, a lever for causing movement of said cams, hydraulic transmission means for transmitting to the latter lever the angular displacements of said oscillating lever and for actuating either of said pneumatic fluid distributors according to the sense of angular movement of said oscillating lever, an oil cock rigid with a fixed portion of the said mount, and means subordinated to the angular displacements of the lever actuating said cams for efiecting in both senses of such angular displacement and subsequent to the opening of one of the said pneumatic fluid distributors the progressive opening of said oil cock.

3. In a gun mount as claimed in claim 2 characterized by the fact that the hydraulic transmission assembly which transmits to the lever actuating the operating cams for the pneumatic fluid distributors an angular displacement corresponding to the angular displacement of the oscillating lever actuated from the movements communicated to the gun about the vertical axis of its universal support includes, a first oil cylinder supported by the movable member, a piston in said cylinder, a piston rod associated with said piston and connected to the end of said oscillating lever, a fixed abutment rigid with said cylinder, a pressure spring between said piston and said abutment, a second oil cylinder rigidly secured to a fixed point of the gun mount, a flexible duct connecting said first oil cylinder with said second oil cylinder, a piston in said second cylinder, a piston rod associated with the latter piston for connection to the lever operating the cams actuating the pneumatic fluid distributors, and. a tension spring between the latter lever and said second oil cylinder.

4. In a gun mount provided on a moving unit, a fixed ring situated in a horizontal plane of said unit, a movable annular member rolling on said fixed ring, a universal joint mounted on said movable ring and supporting the gun, two parallel pneumatic fluid drive cylinders mounted on said unit, a piston in each of said cylinders, cables attached to a point of said movable member and driven by said pistons for eifecting the rotation of said movable member in either sense, guide pulleys for each cable arranged for increasing the range of movement of the portion of cable attached to the movable member with respect to the range of longitudinal movement of the pistons of the pneumatic fluid drive cylinders, an oil cylinder formed in each ofsaid pistons, a fixed piston in each oil cylinder, a pipe for connecting said oil cylinders with each other, a cock in said pipe for controlling the cross section of flow through the latter, a source of pneumatic fluid, ducts for connecting each pneumatic drive cylinder respectively with said source, a pneumatic fluid distributor in each of the latter ducts for putting each of said drive cylinders in communication with said source of pneumatic fluid and the atmosphere alternately, cams actuated by the lateral angular displacements of the gun about the vertical axis of its universal movement, and mechanisms cooperating with said cams for operating successively and according to the sense of the lateral movement communicated to the gun the pneumatic fluid distributor controlling the drive cylinders efiecting the rotation of the movable member in the desired sense and said oil cock, and means for maintaining said pneumatic fluid distributor and cock in operation in every angular position the gun may occupy beyond the angular displacements necessary for actuating said distributor and cock.

5. In a gun mount, a stationary ring, a movable annular member rolling on said stationary ring, a frame pivoted to said movable annular member and normally resting thereon, fluid operated drive means for raising said frame around its points of pivotal connection, distributor means for controlling said drive means, a casing secured to said frame, a spindle rotatably mounted in said casing and normally extending in a perpendicular direction with respect to said movable annular member, a two branch fork at the upper end of said spindle a cradle between the branches of said fork, a gun secured in said cradle, pivots at the ends or the branches of said fork for pivotally supporting said cradle, two parallel cams moving said cradle with the pivotal axis of the cams coinciding with the pivotal axis of the cradle, push rods 00- operating with said cams, parallel guides arranged longitudinally in said spindle for accommodating said push rods, resilient means opposing the sliding movement of the push rods, means operated by said push rods for operating said distributor means when the push rods are actuated by the cams when the gun is being moved angularly in elevation ofi its neutral position, and the profile and arrangement of said cams being such that said distributor means are maintained in operation when the gun is displaced angularly beyond the amount of angular displacement necessary for the operation of said distributor means.

6. In a gun mount, a fixed ring, an annular member movable on said ring, a frame pivoted to said movable annular member and normally resting upon the latter, a gun, a universal joint for supporting said gun on said frame, a drive cylinder operated by compressed air supported by said frame, a piston in said cylinder, an oil cylinder on said frame, a piston in said oil cylinder, a connection between the Piston of said air operated drive cylinder and the piston of said oil cylinder, a source of compressed air, a duct for connecting the air operated drive cylinder with the source of compressed air, a distributor in said duct for controlling the compressed air, two hydraulic jacks for raising the frame interposed between the latter and the movabl member, a pipe for connecting said jacks to said oil cylinder, an oil cock for controlling the section of flow through said pipe, cams moved with the gun when the latter is displaced in elevation oii the neutral position upon its universal joint, means cooperating with said cams for operating said air distributor and oil cook, the profile of said cams being such that when the gun is moved in view of raising the arch the cams cause the opening of the air distributor and the progressive opening of the oil cock and when the gun is moved in view of lowering the frame only the oil cock is opened, and said cams being further effective in keeping the respective fluid control devices in operation when the gun is moved angularly be yond the amount of movement necessary for the operation of said control devices.

ALBERT DEWANDRE. 

